Research on high-pressure air-loop gas flow standard facility

Abstract

Regular calibration of gas flow meters is essential for ensuring their reliable operation. The calibration environment must be consistent with the actual working one to obtain accurate assessment results. In this study, a high-pressure air-loop gas flow meter calibration standard facility has been proposed, and four flow meters with different flow ranges were employed as standard meters. The actual working conditions of flow meters were simulated by precisely controlling pressure and temperature. The facility has a design flow range of (5–2500) m³/h, a working pressure range of (100–2000) kPa, and a working temperature range of (15–30) °C. A two-stage water temperature control system was adopted to ensure that the temperature variation during the test process at each flow point does not exceed 0.2 °C, and the effectiveness of the control method has been proved through experiments. The pressure measurement method used in this facility combined absolute pressure and differential pressure, which reduced the overall expanded uncertainty, which is 0.26 % (k = 2). Experiments were conducted to assess the facility's repeatability, flow stability and capability of rapid flow switching. The results indicated that the facility can be stabilized within 6 min after flow rate switching, and the maximum repeatability of the facility was 0.011 %, the stability during testing time fluctuated by no more than 0.5 %. According to current national verification regulations, this facility can be classified as a 0.33-grade standard facility for verifying and calibrating high-pressure gas flow meters.